Such an alpine anchor has become known with the subject matter of EP 1 750 020 B1 by the same applicant, the anchor being termed spider-shaped anchor in said document.
It comprises substantially a base plate that is placed onto the soil or rock, and threaded rods to be driven through the base plate that are screwed through corresponding threaded bores in the base plate in different directions and at different angles, so as to be anchored in soil or rock likewise at different angles and in different directions.
An alpine anchor of this type has been widely successful. It has been found, however, that assembling the threaded rods into the base plate is difficult, because until now it was known only to use a certain type of drilling machine for the assembly. A known drilling machine of this type comprises a drive motor that drives a drill chuck in the form of a clamp chuck for rotation.
In using such a drilling machine for anchoring, it has been known to clamp the threaded rod by the rear end thereof into the drill chuck or clamp chuck and then position the front end of the threaded rod onto the threaded bore in the base plate and then turn on the drilling machine. Owing to the threaded rod being driven in rotation, the rod was thus progressively driven into the soil or rock, because the thread pitches disposed about the circumference thereof would pull the threaded rod into the soil.
It is a shortcoming of this known assembly method, however, that one must hold the drilling machine or assembly machine free-standing by hand to drive in a relatively long threaded rod with lengths of up to 6 meters. The standard dimension of the threaded rods used is a length of 2 to 4 m, with a threaded rod needing to be driven free-standing through the threaded bores of the base plate while the assembly machine is held unsupported. This presented a great risk of injury, because it could happen that the threaded rods were not clamped-in properly in the clamp chuck and would then be catapulted away during operation of the assembly machine, or it could also happen that the threaded rod would encounter resistance in the soil or rock while the threaded rods were being driven through the threaded bores in the base plate, and would shear off or become jammed, which made it difficult to hold the assembly machine in an accident-free manner.